Security paper, method and device for checking the authenticity of documents recorded thereon

ABSTRACT

A safety paper with an embedded electronic circuit ( 1, 4, 7 ) is used to create more effective forgery-proof securities such as bank notes. In order to check authenticity, a carrier-frequency signal is transmitted to the circuit and an output signal representing an authenticating feature is emitted from raid circuit in response to said input signal and detected.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a safety paper having a structure makingpossible a contactless checking of an authenticity feature and to amethod for checking the authenticity of documents which are recorded inan optically readable form on the safety paper.

2. Description of the Related Art

The use of such safety papers for producing documents serves forprotecting them against unauthorized reproduction by forgers. This isnecessary, in particular, for securities such as bank notes, checks,travelers checks, stocks, etc. There is also a need for securing paperswhich do not have a direct monetary value, such as identificationpapers, passports etc., against unauthorized copying. The employed term“document” is therefore meant to include all types of securities andidentification papers to be protected against unauthorized copying.

In particular, in the case of securities which are circulated daily, forexample, bank notes, a forger may succeed in copying the opticallyrecorded document contents, for example, the optical printed image ofthe bank notes, in a deceptively precise way. A protection against thisis the authenticity feature contained in the safety paper, used forproducing the documents, as a result of the structure imparted to thesafety paper during manufacture which authenticity feature supposedlypractically cannot be copied by a forger with the means available tohim. Moreover, the application of watermarks or the introduction of asafety thread into the paper is known. In particular, it is known (DE 2905 441 C3) to introduce into the paper layer a magnetizable orelectrically conducting safety strip. These conventional measures,however, can no longer be considered satisfactory in view of theadvances of the working means employed by forgers. In particular, in thecase of global political crisis regions the war-conducting groups oreven entire countries employ forgery as warfare. Accordingly, theresources employed for forgery are correspondingly great.

In a bank note produced from a known safety paper of the aforementionedkind (DE 196 30 648 A1), a transponder chip with an antenna isintegrated into the bank note in a way similar to that of safety stripsof different kinds integrated into conventional bank notes. The patternwhich serves as the antenna has the shape of an antenna coil which isformed as a thick or thin layer structure directly on the transponderchip. As an alternative, the transponder chip can be localized in theneighborhood of the metal safety strip or at an interrupted portion ofthe metal safety strip and can be surrounded by the antenna coil.According to a further possibility, the metal safety strip is modifiedsuch that it forms itself the antenna coil for the transponder chip. Theattachment of the antenna coil on the transponder chip itself results ina very small coil cross-section with correspondingly small sending andreceiving sensitivity. Moreover, it is difficult with regard tomanufacturing technology to anchor the small transponder chip on thebank note. The other aforementioned options, in which the antenna coilis arranged outside of the transponder chip on the bank note, providethe possibility of forming greater coil cross-section but the formationand connection of the antenna coil to the transponder chip on the banknote is problematic with regard to manufacturing technology.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a safety paper of theaforementioned kind with improved forgery-proof properties andverification as well as a method and a device for automatic checking ofthe authenticity of the documents produced on the safety paper.

According to the invention, this object is solved with respect to thesafety paper in that the structure is an electronic circuit which emitsan output signal representing the authenticity feature in response to areceived input signal.

According to the inventive embodiment of the safety paper, the checkingwith regard to the presence of the authenticity feature is carried outin that an input signal, which triggers emitting an output signal, istransmitted to the circuit extending within the paper plane. Preferably,the input signal as well as the output signal are in the form of acarrier frequency oscillation modulated with the corresponding signalinformation, respectively. With a corresponding configuration of thecircuit any desired information contents, preferably in binary form, canbe encoded in the output signal as an authenticity feature. It ispossible to provide the electronic circuit with a micro controller. Bydoing so, it is possible to assign at least one individual authenticityfeature, for example, the individual serial number of the microcontroller, to any document produced on the safety paper. For example,in the case of a bank note, this can reside in that the authenticityfeature represents in encoded form the monetary value and/or the serialnumber of the bank note provided on the optically readable printed imageof the bank note. In a method for checking authenticity, the opticallyreadable contents of the document, in the exemplary embodiment themonetary value of the bank note and/or its serial number, and the outputsignal of the circuit encoding the contents can be automaticallydetected and compared with one another. The authenticity of thedocument, for example, the bank note, is confirmed by this method onlywhen between the optically read contents and the information contents ofthe output signal of the circuit a predetermined correlation, forexample, content identity, is present.

A method and a document according to embodiments of the inventionparticularly take into account that especially bank notes can beseparated into two parts and the respectively missing part can bereplaced by forgery. By providing a generally invisible authenticityfeature, which can however be detected by technical means, for example,magnetically or by light not within the visible range, in one part andby storing information corresponding to this authenticity feature in thecircuit on the other part, the two parts are coupled to one another in aforgery-proof way. The information contents corresponding to thedetected authenticity feature is entered into the circuit during theauthenticity check and is checked therein with regard to authenticity,for example, by comparison to reference information. The circuit onlyprovides the output signal acknowledging authenticity when thisauthenticity check is positive.

An expedient embodiment of the inventive concept is that the structureforming the circuit comprises a read-only storage having a predeterminedinformation contents, wherein the information contents can betransmitted with the emitted output signal. In this connection, theinformation contents corresponding to the authenticity feature ispermanently pre-set in the read-only storage and is transmitted with theemitted output signal.

In the context of the invention it is also provided that the structureforming the circuit comprises a write/read storage into which theinformation contents transmitted by the received input signal can bewritten, wherein the transmitted information contents can be transmittedwith the emitted output signal.

In this embodiment, the input signal not only serves to access thefixedly adjusted authenticity feature which is permanently correlatedwith the document produced on the safety paper; moreover, theinformation contents can be transmitted to the circuit with the inputsignal and can be stored therein and, in response to a subsequentlyreceived receiving signal, can also be transmitted with the emittedoutput signal. This embodiment is especially important with respect toanother method variant. In this connection, at each location whichexamines the document produced on the safety paper, for example, at eachbank which receives a bank note during its circulation, the examininglocation and optionally also the date of the examination, representingthe information contents, is written into the circuit with the inputsignal during the checking process, for example, during a money countingprocess. During the subsequent checking processes, this informationcontents is transferable by means of the emitted output signal andprovides in this way a local and temporal proof of stations which havebeen passed. Unauthorized money-laundering activities can thus beprecisely traced.

With respect to circuit-technological considerations, this is realizedespecially simply in that the write/read storage is formed by a shiftregister into which the binary representation of the informationcontents transmitted by the input signal can be sequentially stored. Inthis connection, the length of the shift register, as a function of themagnitude of the information contents transmitted by the individualexamination locations, determines the total number of storable checkingactivities. Since the information contents are pushed through from theinput of the shift register to its output, the latter always containsthe most recent state of these information contents while theinformation contents of examinations that ate not so recent and surpassthe storage capacity of the shift register are moved out of the shiftregister.

Another important principle of the invention resides in that thestructure forming the circuit comprises an energy supply which can berecharged by contactless energy transmission. In this respect, it isespecially expedient that the energy transmission is realized by acarrier frequency oscillation provided for modulation with the inputsignal. By doing so, the energy supply of the circuit can be realizedcompletely from the exterior, and the circuit does not require its ownoperating energy source; as a result of its limited service life and thefact that, in any case, it can hardly be formed paper-thin with currentmeans, providing such energy source would present great difficultieswith regard to a practical and economical realization of the safetypaper.

Different possibilities are conceivable in regard to how to manufacturethe circuit in or on the safety paper. One of these possibilitiesprovides that the structure forming the circuit is embedded in the paperlayer of the safety paper. In this case, the circuit is covered on bothsides by partial layers of the paper layer. In contrast, another veryexpedient alternative is that the pattern which forms thesending/receiving antenna is applied externally to the paper layer andis coupled by the paper layer, which serves as a dielectric, in acapacitive way to the remaining portion of the circuit embedded in thepaper layer. This alternative can be produced, for example, in that theremaining part of the circuit is pre-manufactured on a thin flexiblesubstrate and is introduced into the paper layer during the papermanufacture while the antenna pattern is applied, for example, byprinting, onto the paper layer provided with the embedded part of thecircuit. Between the connecting portions of the pattern, serving as asending/receiving antenna, arranged on the paper layer and the areas ofthe embedded flexible substrate serving as connecting portions for theremaining part of the circuit, a part of the paper layer acting as thedielectric is therefore provided, respectively, which, together with theconnecting portions, positioned above one another on both sides of thispart of the paper layer, of the antenna pattern and of the embeddedflexible substrate, forms a capacitor effecting a capacitive coupling.

In a preferred embodiment of the safety paper it is provided that thestructure forming the circuit comprises an electronic circuit chip and apattern connected therewith and serving as a sending/receiving antenna.The conductor pattern forming the sending/receiving antenna allows aneffective signal transmission, in particular, when realized by amodulated carrier frequency to which the antenna pattern is tuned. Sincethe surface area of the circuit is very small in comparison to theformat surface of the bank notes and other documents, plenty of space isavailable for the antenna pattern.

An especially expedient embodiment is realized in that the structureforming the circuit comprises an integrated polymer circuit chip whichis formed on a flexible polymer substrate. This embodiment takesadvantage of the known modern polymer circuit techniques (compare IEDM97-331 “Polymeric Integrated Circuits and Light-Emitting Diodes” or TheAmerican Association for the Advancement of Science, vol. 278, No. 5337,17 Oct. 1997, pp. 383-384 “Patterning Electronics on the Cheap”).

Preferably, the pattern serving as the sending/receiving antenna has theshape of a dipole antenna.

Because of its simple straight form, the dipole antenna makes possible asimple manufacture of the safety paper. In particular, it can berealized as a straight linear strip across a large paper web, whereinthe individual dipole antennas of the documents to be produced from thepaper web by cutting are produced automatically by the cutting process.The sending/receiving directional characteristic connected with thedipole antenna is also advantageous. For example, bank notes which arestacked are conventionally counted in counting machines such that therespectively uppermost bank note of the stack is turned about one of itslonger lateral edges and is then placed onto a new stack. Inasmuch asthe dipole antenna extends perpendicularly to this lateral edge, itpasses during this turning process through a plane which extendsperpendicularly to the stack plane so that, for a suitable alignment ofthe sending/receiving characteristic of the counting machine, thecoupling for the bank note, aligned during the turning movementperpendicularly to the stack plane, is at a maximum and a feedover ofthe other bank notes of the stack is suppressed. It is understood thatthe modulated carrier frequency used for the signal transmission isadjusted to the size of the dipole antenna.

Various possibilities are conceivable in regard to how to realize thecircuit chip and its dipole antenna on the safety paper. Preferably, itis suggested that the pattern which forms the dipole antenna iscomprised of two conductor strips extending along a common straight linewhich are contacted via their oppositely positioned ends with connectingareas of the circuit chip. In this connection, it is particularlyexpedient that the two conductor strips are formed by portions of aninsulating thin polymer substrate strip that have been made conductingbetween whose insulating portion, delimited by the ends of the conductorstrips facing one another, the circuit chip is arranged. The conductingportions of the insulating thin polymer substrate strips can begenerated, for example, by doping. It is also very expedient tometallize, i.e., to provide with a thin metal layer, a larger polymerweb with the exception of the insulating portions serving for receivingthe circuit chips and to produce the polymer substrate strips therefromby cutting. In the case of producing the conductivity by metallizationof one side of the polymer substrate strip, the other side can beprovided, as an additional measure, with a photovoltaic layer which canserve as an exclusive or additional supplier of operational energy forthe circuit. Furthermore, it is expedient to provide the conductor stripwith cutouts, in particular, fine perforations, so that the clampingaction with the paper layer is improved.

The connection with the circuit chip can be realized in that the circuitchip is formed on a thin-ground semiconductor substrate which isarranged on the insulating portion of the polymer substrate strip.Techniques for thin grinding of the semiconductor substrate are known.

As an alternative, it can be provided that the circuit chip is anintegrated polymer circuit chip formed on a flexible polymer substrateprovided with a pattern forming the dipole antenna. This embodimenttakes advantage of the known modern polymer circuit techniques (compareIEDM 97-331 “Polymeric Integrated Circuits and Light-Emitting Diodes” orThe American Association for the Advancement of Science, vol. 278, No.5337, 17 Oct. 1997, pp. 383-384 “Patterning Electronics on the Cheap”).

An embodiment which is advantageous in all situations resides in thatthe circuit chip and the pattern forming the dipole antenna are embeddedin the paper layer of the safety paper. In this case the circuit chipand the dipole antenna are covered on both sides by partial layers ofthe paper layer.

Another basic principle of the invention resides in that the structurecomprises an electro-optical surface area containing the authenticityfeature whose light reflection or transmission properties can becontrolled as a function of an electrical potential supplied to thesurface area. In this case, the authenticity feature can be formed inthe surface area, for example, in the form of a document number or banknote number or other identification symbols in positive form or negativeform. During the authenticity check the control potential is supplied tothis surface area. The thus caused change of the light reflection ortransmission then allows optical recognition of the authenticityfeature.

As in the afore described embodiments, the required potential forcontrolling the electro-optical surface area can be generated bycontactless introduction of HF energy. An especially advantageousalternative in regard to electrical energy supply, however, resides inthat the structure comprises a photovoltaic surface area which serves asan energy supplier. In this case, during the safety check it is onlyrequired to supply light onto the photovoltaic surface area of thesafety paper. The photovoltaic surface area provides in response to theinput light the electrical operating energy for the safety structure.This particularly advantageous kind of energy supply is not limited tosafety paper and documents produced therefrom. It is also suitable, inparticular, for the contactless energy supply of intelligent hardplastic cards, as known, for example, in the form of smart cards andsimilar plastic cards with integrated electronic components used, inparticular, for payments.

Such electro-optically controlled surface areas can be produced, inparticular, by sputtering methods with which, in vacuum or in specialgas atmospheres, metals or metal alloys can be applied in thin layers onthin plastic films. The thus coated plastic films, whose coating hasbeen generated during the coating process, or also subsequently thereto,as a pattern that represents the authenticity feature in a positive ornegative form, can then be applied onto the safety paper or embedded inits paper layer.

The invention also provides a device for contactless checking ofauthenticity of a document made of a safety paper which is provided withan electronic circuit chip as well as with a pattern connected therewithand being in the form of a dipole antenna having two dipole branchesextending along a common straight line and serving as asending/receiving antenna, wherein the electronic circuit chip inresponse to a received input signal emits an output signal representingthe authenticity feature, wherein the device has a transport device bywhich the document to be checked can be transported along a movementpath extending transverse to the common straight line of the dipolebranches, two conductors extending in the transport direction, onearranged in the area of the movement path of one dipole branch and theother in the area of the movement path of the other dipole branch for acapacitive coupling with the moving dipole branches, respectively, and asending/receiving device coupled with the two conductors for emittingthe input signal for the circuit chip and for receiving its outputsignal representing the authenticity signal.

In this checking device embodied according to the invention, the twoconductors serving as the antenna for the sending/receiving device ofthe checking device extend over a sufficient length of the movement pathof the document to be checked so that over this entire path length auniformly strong coupling to the dipole antenna of the respectivedocument to be checked is ensured. The dipole antenna of the document tobe checked can have a relatively minimal extension in the transportdirection while the two conductors of the checking device arecomparatively long in comparison thereto.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following description the invention is explained in an exemplaryfashion with reference to the drawing. It is shown in:

FIG. 1 a plan view onto the front side of a travelers check on which therealization of an electronic circuit which serves for authenticitychecking is schematically indicated;

FIG. 2 a view onto the backside of the travelers check illustrated inFIG. 1;

FIG. 3 a view corresponding to FIG. 1 of another embodiment;

FIG. 4 a plan view onto the backside of the embodiment of FIG. 3;

FIG. 5 a schematic illustration of a checking device; and

FIG. 6 an embodiment variant of FIG. 1 in a plan view.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The travelers check of an internationally known bank illustrated in thedrawing is supplemented for the purpose of explaining the invention bythe schematic illustration of an electronic circuit. The latter has apolymer strip 1 which is made conductive by doping and is embedded inthe paper layer. This can be realized in a manner known in the art inthat during the paper manufacture first the first partial layer of thepaper pulp is deposited, the polymer strip 1 is placed thereon, and,subsequently, a second partial layer of the paper pulp is applied. Thepolymer strip 1 extends parallel to the two shorter lateral edges 2, 2′over the entire width of the rectangular travelers check up to itslonger lateral edges 3, 3′. Even though the polymer strip 1 is coveredon both sides by the paper layer, it is illustrated in the drawing so asto show through the layers covering it.

In the center of the polymer strip 1 an integrated polymer circuit chipis formed whose external terminals are formed by the two partial strips5, 5′ of the polymer strip 1 extending on-both sides of the polymercircuit chip 4. The two partial strips 5, 5′ are coupled at their ends6, 6′positioned on the longer lateral edges 3, 3′ capacitively orelectrically with the antenna pattern 7 which extends, starting at theends 6, 6′, in the form of a conductor along the two longer lateraledges 3, 3′ and the shorter lateral edge 2 connecting these two lateraledges.

The antenna pattern 7 could also be embedded during the papermanufacture in the paper layer in that it is generated, for example, byprinting it onto the first deposited partial layer of the paper pulp.However, the antenna pattern 7 is printed in a simpler way and withoutsafety loss externally onto the paper layer provided with the embeddedpolymer strip 1. In this case, the ends of the antenna pattern 7positioned above the polymer strip 1 overlap the ends 6, 6′ of the twopartial strips 5, 5′ positioned on the longer lateral edges 3, 3′ withinthe paper layer, wherein between the overlapping areas of the antennapattern 7 and the polymer strip 1 a partial layer of the paper layer isenclosed, respectively. This partial layer thus acts as a dielectric bywhich the antenna pattern 7 is coupled capacitively with the polymerstrip 1 provided with the polymer circuit chip 4.

The polymer circuit chip 4 forms a micro controller with a read-onlystorage, a shift register serving as a write/read storage, and aninput/output unit which comprises a receiving portion and a sendingportion. The number as well as the monetary value of the travelers checkprinted on the front side of the travelers check as optically readableplain text are stored in the read-only storage.

The checking of the authenticity requires the travelers check to beguided through a checking device which reads, on the one hand, theprinted, optically readable data such as check number and monetaryvalue. At the same time, this reading device emits a carrier-frequencybased, modulated input signal for the circuit 1, 4, 7. This input signalis decoded in the receiving portion of the circuit. In response to this,the micro controller controls the read-only storage and the sendingportion for a carrier frequency modulated emission of an output signalin which the information contents of the read-only storage is encoded.The checking device detects this output signal and compares theinformation contents transmitted therewith with the optically detectedplain text data of the travelers check. If no match is detected, thetravelers check is identified as forged.

An even higher safety is achieved when the document, for example, thebank note or travelers check, is provided additionally with anauthenticity feature, which is not optically readable but readable byother technical means, for example, by UV light or magnetically, at alocation which differs from the location of the circuit. In this case,the checking device detects this authenticity feature and transmits theinformation corresponding to the detected authenticity feature to thecircuit. Here, the authenticity feature is checked internally, forexample, by comparison with a reference information stored in thecircuit. The circuit emits an output signal indicating authenticity tothe checking device only in the case of a positive checking result.

The checking location transmits with the input signal an informationcontents identifying it, for example, the name and place of the bankreceiving the travelers check in addition to the date of the checkingoperation. At the same time, the receiving bank can transmit and storewith the input signal identifying information of the person submittingthe travelers check, for example, the name and address. This informationidentifying the person submitting the check is of interest, inparticular, when a location which has received the travelers checkoriginally from the issuing person, transfers this travelers check to athird person as legal tender and this third person appears at the bankas the person redeeming the check. This identification information isentered by the micro controller in binary form serially into the shiftregister wherein, if needed, a portion of previously entered informationoverflows at the output of the shift register and is lost.

The input signal transmitted from the checking device to the circuit canalso be encoded with a command for reading the contents of the shiftregister with simultaneous re-writing of the read information contents.By transmitting the entire contents of the shift register in the outputsignal of the circuit, the checking device can detect and process thisinformation contents. In this way, it is possible to determine with thechecking device through which checking locations the document to bechecked has already passed previously and at what point in time. This isparticularly important when the documents are bank notes provided withthe circuit 1, 4, 7 which, during the course of their circulation, arecounted again and again by the receiving banks. In this way, thecirculation path of these bank notes can be monitored.

In the case of travelers checks their safety can be further enhanced inthat the drawee bank, when issuing the travelers check, can store anidentification code, for example, a pin code, that the check owner hasagreed to, in the read/write storage. Inasmuch as the receiving locationaccepting the travelers check is provided with a suitable device forreading this additional identification code, it can request, forauthenticity checking, this additional identification code to bedisclosed by the issuer of the check in order to compare it with theread version of the additional identification code. Should no match bepresent, the travelers check is to be disposed of as forged.

An energy supply, which is integrated in the polymer circuit chip 4 andsupplies the operating energy for the circuit 1, 4, 7 provided on thetravelers check, is supplied by the carrier frequency oscillation of theinput signal transmitted by the checking device. In this way, thechecking device transmits the required energy for the operation of thecircuit.

It is understood that the employed safety paper for the manufacture ofthe afore described travelers check is produced in the form of webswhich, according to the format, have the polymer strips 1 embeddedtherein as continuous strips and are provided with the correspondingantenna pattern. This paper web is subsequently printed on both sidesand is then cut to size according to the desired format so that theindividual pieces of travelers checks or the like are generated.

In the embodiment illustrated in FIGS. 3 and 4, the travelers check hasan electronic circuit which is formed by a thin chip 40. The chip 40 isarranged on a polymer strip 10 which is embedded in the paper layer.This can be carried out as is known in the art in that during the papermanufacture first a first partial layer of the paper pulp is deposited,the polymer strip 10 is placed thereon, and subsequently a secondpartial layer of the paper pulp is applied. The polymer strip 10 extendsparallel to the two shorter lateral edges 20, 20′ over the entire widthof the rectangular travelers check up to its longer lateral edges 30,30′. Even though the polymer strip 10 is covered on both sides by thepaper layer, it is illustrated in the drawing so as to show through thelayers covering it.

The polymer strip 10 is, for example, made conductive by doping or by anapplied metallization. Only in the center between the two lateral edges30, 30′ where the integrated circuit chip 40 is arranged, the conductivedoping or metallization layer is interrupted such that connecting areasof the chip 40 formed on oppositely positioned edges 70, 70′ of the chip40 are contacted by one of the two partial strips 50, 50′ of the polymerstrip 10 extending on both sides of the interrupted portion,respectively. The two partial strips 50, 50′ form in this way a dipoleantenna connected to the chip 40 which serves for signal transmission aswell as transmission of operating energy for the chip 40.

Like the polymer circuit chip 4 of the embodiment of FIGS. 1 and 2, thecircuit chip 40 of the embodiment of FIGS. 3 and 4 also forms a microcontroller with a read-only storage, a shift register serving as awrite/read storage, and an input/output unit comprising a receivingportion and a sending portion. In the read-only storage the number aswell as the monetary value of the travelers checks printed on the frontside of the travelers check in optically readable plain text arepermanently stored. The checking for authenticity is carried out in thesame way as explained above for the embodiment of FIGS. 1 and 2.

Bank notes have the same appearance as the travelers check explained inconnection with FIGS. 1 and 2. The counting of such bank notes iscarried out usually in that from a stack of bank notes to be counted theuppermost bank note, respectively, is turned about one of its longerlateral edges 30 or 30′ and is in this way transferred onto a countedstack. During this turning process the conductor strips 50, 50′ formingthe dipole antenna pass through a plane which is perpendicular to thelonger lateral edges 30, 30′ so that the conductor strips 50, 50′ at thecenter of this turning movement are positioned perpendicularly to theplane of the bank notes which are positioned on the stack to be countedor on the stack already counted. By using the directional characteristicof the dipole antenna, the checking device can be arranged such that themaximal coupling to the dipole antenna 50, 50′ is achieved in the centerof the turning path of each bank note between the stack to be countedand the counted stack. Accordingly, feedover of the bank notespositioned on both stacks can be suppressed during the counting process.

As with the embodiment of FIGS. 1 and 2, an energy supply integrated inthe circuit chip 40 and providing the operational energy is supplied bythe carrier frequency oscillation of the input signal which istransmitted by the checking device. As an alternative or in addition,the operating energy could be derived from a photovoltaic area arrangedon the document. In this way, the checking device transmits the requiredenergy for the operation of the circuit chip 40.

The safety paper is produced in the form of webs in which, according tothe format of the bank notes, travelers checks, documents etc. to beproduced from the safety paper, the polymer strip 10, with the chips 40arranged thereat at a spacing corresponding to the spacing of thelateral edges 30, 30′, is embedded so as to extend continuously. Thispaper web is subsequently printed on both sides and then cut to sizeaccording to the desired format so that the individual pieces of banknotes, travelers check or the like are generated in which the partialstrips serving as a dipole antenna extend with their ends 60, 60′ to thelateral edges 30, 30′ of the cut pieces.

FIG. 5, in which the essential parts of a checking device areschematically illustrated, shows a document 100 to be checked, forexample, a bank note, which is transported by a transport device, notrepresented, in a transport direction illustrated by arrow 101 along amovement path. The document 100 corresponds to the embodimentillustrated in FIGS. 3 and 4. The alignment of the document 100 is suchthat the two conductor strips 50, 50′ connected to the circuit chip 40and forming the dipole antenna extend transverse to the transportdirection 101.

The checking device has two elongate conductors 103, 103′ which extendwith their longitudinal direction along the transport direction 101 andare arranged such that one conductor 103 is arranged in the area of themovement path of one dipole branch 50 and the other conductor 103′ inthe area of the movement path of the other dipole branch 50′. In thisway, the document 100 during movement through the checking device iscoupled capacitively with uniform strength to the two conductor paths103, 103′. The latter serve as a sending/receiving antenna for asending/receiving device 104 of the checking device connected thereto.In this way, the input signal for the circuit chip 40 is reliablytransmitted from the sending/receiving device 104 of the checking deviceand the output signal emitted by the circuit chip 40 is reliablyreceived.

The embodiment illustrated in FIG. 6 deviates from that of FIGS. 1 and 2only with respect to the positional arrangement of the circuit chip 4.Otherwise, there is complete identity with the embodiment of FIGS. 1 and2, and, therefore, reference is being had to the above description,wherein in FIG. 6 the same reference numerals are used for the partsidentical to those of FIG. 1.

FIG. 6 illustrates in deviation of FIG. 1 the asymmetric position of thecircuit chip 4 on the document relative to the two transverse edges 2,2′ and the two longitudinal edges 3, 3′. In this way, the circuit chip 4avoids the area of the longitudinal centerline extending in the centerbetween the two longitudinal edges 3, 3′ and parallel thereto and alsothe area of the transverse centerline of the document extending in thecenter between the two transverse edges 2, 2′ and parallel thereto.Inasmuch as the document, in particular, a bank note, is folded alongthe two imaginary center lines, the circuit chip 4 is not affected bythis folding action. This means that during conventional folding no riskof damage is present. This asymmetric positional arrangement of thecircuit chip 4 is advantageous for all embodiments, in particular, alsofor the arrangement of the circuit chip 40 of the embodiment illustratedin FIGS. 3 and 4.

Often, documents, in particular, bank notes, have an area which is notprinted. In this area there is often a watermark in the paper layer. Inall embodiments it is advantageous to arrange the circuit chip 4 or 40in such areas without printed image so that the loading of the circuitchips during the later printing process is avoided.

In all embodiments it is also advantageous that the pattern serving asthe sending/receiving antenna is produced of a material whose expansioncoefficient substantially matches the expansion coefficient of the paperlayer connected to the pattern. Distortions or warping of the safetypaper or even detachment of the pattern can thus be prevented.

1. A safety paper with a) a structure in the form of an electroniccircuit (1, 4, 7) making possible a contactless checking of anauthenticity feature, b) the circuit (1, 4, 7) comprising an electroniccircuit chip and a pattern (7) connected therewith and serving as asending/receiving antenna that, c) the electronic circuit, in responseto a received input signal, is operative to emit emits an output signalindicating the presence of the authenticity feature, d) the and whosepattern (50, 50′) serving as a sending/receiving antenna has the form ofbeing formed as a dipole antenna comprised of two conductor strips (50,50′) extending along a common straight line, e) which at facing endsthereof are contacted with connecting areas (70, 70′) of the circuitchip (40), f) the conductor strips and are formed by portions of a thininsulating polymer substrate strip that have been made conductive,between whose g) the circuit chip is positioned on an insulatingportion, delimited between the facing ends of the conductor strips (50,50′), the circuit chip (40) is positioned, wherein h) the circuit chip(40) is formed on a thin-ground semiconductor substrate which isarranged on the insulating portion of the polymer substrate strip.
 2. Asafety paper with a structure in the form of an electronic circuit (1,4, 7) making possible a contactless checking of an authenticity feature,the circuit (1, 4, 7) comprising an electronic circuit chip and apattern (7) connected therewith and serving as a sending/receivingantenna that, in response to a received input signal, emits an outputsignal indicating the presence of the authenticity feature and whosepattern (50, 50′) serving as a sending/receiving antenna has the form ofa dipole antenna comprised of two conductor strips (50, 50′) extendingalong a common straight line, which at facing ends thereof are contactedwith connecting areas (70, 70′) of the circuit chip (40) and are formedby portions of a thin insulating polymer substrate strip that have beenmade conductive, between whose insulating portion, delimited between thefacing ends of the conductor strips (50, 50′), the circuit chip (40) ispositioned, wherein the structure forming the circuit (1, 4, 7)comprises an integrated polymer circuit chip (4) formed on a flexiblepolymer substrate.
 3. A safety paper with a structure in the form of anelectronic circuit (1, 4, 7) making possible a contactless checking ofan authenticity feature, the circuit (1, 4, 7) comprising an electroniccircuit chip and a pattern (7) connected therewith and serving as asending/receiving antenna that, in response to a received input signal,emits an output signal indicating the presence of the authenticityfeature, wherein the pattern serving as a sending/receiving antenna isapplied externally to the paper layer and is coupled capacitively by thepaper layer, acting as a dielectric, to a remaining portion of thecircuit embedded in the paper layer.
 4. A safety paper according claim1, wherein a structure forming the circuit (1, 4, 7) comprises aread-only storage set to a predetermined information contents, whoseinformation contents can be transmitted with the emitted output signal.5. A safety paper according to claim 1, wherein a structure (1, 4, 7)forming the circuit comprises a write/read storage into whichinformation contents transmitted by the received input signal can bewritten whose information contents can be transmitted with the emittedoutput signal.
 6. A safety paper according to claim 5, wherein thewrite/read storage is formed by a shift register into which a binaryrepresentation of the information contents transmitted with the inputsignal can be sequentially stored.
 7. A safety paper according to claim1, wherein a structure (1, 4, 7) forming the circuit comprises an energysupply which can be supplied by a contactless energy transmission.
 8. Asafety paper according to claim 7, wherein energy transmission can berealized by a carrier frequency oscillation provided for modulation withthe input signal.
 9. A safety paper according to claim 1, wherein astructure forming the circuit (1, 4, 7) is embedded in a paper layer ofthe safety paper.
 10. A safety paper according to claim 1, wherein thepattern (1, 5, 5′, 7, 50, 50′) serving as a sending/receiving antenna iscomprised of a material whose expansion coefficient correspondssubstantially to the expansion coefficient of the paper layer.
 11. Asafety paper according to claim 1, wherein the circuit (1, 4, 7; 40, 50,50′, 70, 70′) comprises a micro controller.
 12. A document made of asafety paper according to claim 1, wherein the circuit chip (4, 40) isarranged in an area of the document that is not printed.
 13. A documentmade of a safety paper according to claim 1, wherein, in an area whichis remote from the area in which the electronic circuit (4, 40) isarranged, an authenticity feature is arranged that is detectablecontactless and can be input into the circuit and checked therein.
 14. Amethod for checking the authenticity of documents which are recorded inan optically readable form on a safety paper with a structure in theform of an electronic circuit making possible a contactless checking ofan authenticity feature, the circuit, in response to a received inputsignal, emitting an output signal representing the authenticity feature,comprising transmitting an input signal by the location checking thedocument to the circuit which triggers the emission of its output signaland the optically readable contents of the document as well as theauthenticity feature are automatically detected and correlated with oneanother, wherein the input signal transmitted by the checking locationto the circuit comprises and information contents which identifies thechecking location and is stored in the circuit, wherein the storedinformation contents, which identifies the checking location, can betransmitted with the output signal to a checking location in response toan input signal transmitted subsequently by the checking location.
 15. Amethod according to claim 14, wherein the energy for operating thecircuit is transmitted by the checking location with the input signal tothe circuit.
 16. A device for a contactless checking of authenticity ofa document made of a safety paper, the document which is provided withan electronic circuit chip as well as a pattern connected thereto andserving as a sending/receiving antenna, the pattern serving as asending/receiving antenna is and formed as a dipole antenna with dipolebranches extending along a common straight line, wherein the electroniccircuit chip, in response to a received input signal, emits is operativeto emit an output signal representing the authenticity feature, thedevice comprising: a transport device by which the documents (100) to bechecked are transported along a movement path extending transverse tothe common straight line of the dipole branches (50, 50′);, twoconductors (103, 103′) extending in the transport direction (100), oneof them arranged in the area of the movement path of the one dipolebranch (50) and the other in the area of the movement path of the otherdipole branch (50′), respectively, for capacitive coupling with themoving dipole branches (50, 50′);, and a sending/receiving devicecoupled with the conductors (103, 103′) for emitting the input signalfor the circuit chip (40) and for receiving the output signalrepresenting the authenticity signal.